This invention relates to a method of producing heat for an area heating system remote from a thermal electric power station and to said power station for performing the said method.
Power stations used for remote area heating have the disadvantage that the efficiency drops owing to the elevated condensation temperature, so that the power yield for any given primary energy consumption is considerably less than in the case of conventional power stations. Since the temperature gradient in nuclear power stations is less than in fossil fired power stations, this advantage is particularly pronounced in the former.
The object of the invention is the utilisation of the waste heat from power station installations used for remote area heating, in which the efficiency of such installations is not subject to any load-dependent reduction.
The invention fulfils this object in a method of producing remote heat in power station installations, in which waste heat appears at a different temperature in dependence on the electric power generated, in that firstly the return water from the remote heating grid is subjected to the waste heat which is given off at a low temperature, that thereafter this water is stored and that finally this water is heated further by waste heat given off at a higher temperature and supplied to the inlet to the remote heating grid.
One way of performing this method is to utilize a multi-stage turbine which has at least one steam discharge between adjacent stages of the turbine and to provide a condenser downstream of the steam discharge. A further steam discharge is located downstream of the last stage of the turbine with a second condenser connected thereto. A water storage vessel is provided to which the cooling water of the second condenser is admitted during the period of peak load and from which the cooling water stream for the first condenser is withdrawn during the off-peak load period.
A further embodiment consists in that in power station installations, consisting of a base-load steam turbine installation with a condenser and a peak-load generator with a gas engine, e.g. a gas turbine, the latter being, if desired, arranged spatially separate from the former, the invention is seen in taking the input to the remote heating grid through a condenser and thereafter supplying it to a storage vessel from which the water for receiving the waste heat from the gas engine is withdrawn and supplied to the input to the remote heating grid.
In each case the quantity of water required for disposing of the heat is intermediately stored in a storage tank located in the vicinity of the power station. This storage tank is, for example, charged in the course of the day with water which has been pre-heated by condensation of the fully de-energised steam. During the night, during which in any case the electricity demand is less than during the day, the turbine unit is run at a lower energy level. The steam which has been tapped off is supplied to the condenser, which is now cooled by the water which has already been heated during the day, the water which has been preheated during the day being heated up to the required temperature at which it is utilised in the remote heating grid. The cooling water is discharged during the night preferably at an intermediate level of the storage vessel, whereas the fully heated water is returned in the upper region of the storage vessel. Preferably a device is provided at an intermediate level which discharges the water of that layer which has the correct temperature for any particular requirement. During the night the water volume which has been heated during the day and which has been stored at an intermediate temperature, is used up, and the vacated storage volume is again recharged by cold return water from the remote heating grid.
The invention will now be described with reference to the drawings.